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osanseviero
 3 years ago
I need to write a program that that prints the longest substring of s in which the letters occur in alphabetical order.
For example, if s = 'azcbobobegghakl', then your program should print beggh
How should this start?
osanseviero
 3 years ago
I need to write a program that that prints the longest substring of s in which the letters occur in alphabetical order. For example, if s = 'azcbobobegghakl', then your program should print beggh How should this start?

This Question is Closed

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3hmm... well, you could look at each character and see if it is <= the next. Count how many are, then make a sub string based on that. The issue is when to discard it if you find a larger string.

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3azcbobobegghakl az alphabetical, but len 2. zc bad cb good, but not loneger cbo good, 3, drop the 2. ob bad bo good, but not loneger ob bad be good, but not loneger beg good, but not loneger begg good, loneger drop the 3 beggh good, loneger drop the 4 ha bad ak good but not longer akl good but not longer

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3That is basically what it would do. Now for the how, use ifs and boolian comparisons.

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0so i keep creating substrings and comparing lengths, and depending on their lengths i will keep the largest one

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3Well, you only need two bufer strings. The longes one as the answer and the now being worked on one. If the now worked becomes longer than the answer, replace the answer. >>> 'a'<'b' True >>> 'c'<'b' False >>>

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0How can I compare it with values from before?

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3Testing each character as you go will let you decide if it is time to reset the buffer string or to add to it.

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0I need to rest.I will come back in some hours

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3OK. This should give you something to start with. You can see what it would do and some info on how. Work with that and see how far you get.

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0In human talking, this would be done with this: 1. Take the first character 2. Save it. 3. Take the second character. 4. Compare them Option 1: a. If first character is bigger than the second one, FALSE statement, continue with first character as the substring. b. If first character is smaller, TRUE statement, new substring is first character + second one. 5. Repeat

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0But this would just work for a continued string...I dont know how it would be done for a new substring

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3Well, if the first character is bigger, then you want to reset or erase the buffer string. If it is smaller, then you want to add it to the buffer string.

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3And after every time through those, you want to see if the buffeer string is longer than the answer string. If so, replace the answer string with the buffer string.

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0Why does this give a number as an answer? s=raw_input("Enter a word: ") buffer="" for i in range(len(s)1): if s[i]<=s[i+1]: buffer=str(i)+str(i+1) if s[i]>=s[i+1]: buffer=buffer print("Longest substring in alphabetical order is: " + str(buffer))

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3dw:1382852135152:dw

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3buffer=str(i)+str(i+1) buffer=str[i]+str[i+1] You need to use [ ] for string arrays. And you only want to work on one character at a time.

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0why are the results numbers?

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3str(i) is not the same as str[i]

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3``` >>> s = "this is a test" >>> s[1] 'h' >>> i=1 >>> s[i] 'h' >>> s(i) Traceback (most recent call last): File "<interactive input>", line 1, in <module> TypeError: 'str' object is not callable ```

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0It never gives me an answer :/ s=raw_input("Enter a word: ") substring="" for i in range(len(s)1): if s[i]<s[i+1]: substring=str(i) + str(i+1) if s[i]>=s[i+1]: substring="" print("Longest substring in alphabetical order is: " + str(substring))

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3Like I said, you will need two buffers to hold strings. Also, you still have str(i). That is the numbers. You need s[i]. Also, this is how you turn multiple things into one but keep the first thing as part: ``` >>> a = 'abc' >>> b = 'def' >>> c = 'hij' >>> a 'abc' >>> a = a + b + c >>> a 'abcdefhij' >>> ```

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0I have two hours to finish this :/ Can you give me a push?

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0It throws me this :( string indices must be integers, not str

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0s=raw_input("Enter a word: ") substring="" output="" for i in range(len(s)1): if s[i]<s[i+1]: substring=substring+s[i] if len(substring)>len(output): output=substring else: substring="" print output

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0Forget it, no more time. I still want to achieve this

anonymous
 3 years ago
Best ResponseYou've already chosen the best response.0@e.mccormick doen't leave any question unanswered

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3Some possible flow of control issues.

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3Forgot to put all the yes/no on that.

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3I also realized that you need to test the last character in there somewhere, which is why that has another if in it.

osanseviero
 3 years ago
Best ResponseYou've already chosen the best response.0which is the use of for i=0?

e.mccormick
 3 years ago
Best ResponseYou've already chosen the best response.3It is a way of showing a for loop in a diagram.
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